Ostracods in permafrost deposits from the Bykovsky Peninsula 1998/1999@en

Ostracode analysis was carried out on samples from ice-rich permafrost deposits obtained on the Bykovsky Peninsula (Laptev Sea). A composite profile was investigated that covers most of a 38-m thick permafrost sequence and corresponds to the last ca. 60 kyr of the Late Quaternary. The ostracode assemblages are similar to those known from European Quaternary lake deposits during cold stages. The ostracode habitats were small, shallow, cold, oligotrophic pools located in low centred ice wedge polygons or in small thermokarst depressions. In total, 15 taxa, representing 7 genera, were identified from 65 samples. The studied section is subdivided into six ostracode zones that correspond to Late Quaternary climatic and environmental stadial-interstadial variations established by other paleoenvironmental proxies: (1) cold and dry Zyrianian stadial (58-53 kyr BP); (2) warm and dry Karginian interstadial (48-34 kyr BP); (3) transition from the Karginian interstadial to the cold and dry Sartanian stadial (34-21 kyr BP); (4) transition from the Sartanian stadial to the warm and dry Late Pleistocene period, the Allerød (21-14 kyr BP); (5) transition from the Allerød to the warm and wet Middle Holocene (14-7 kyr BP); and (6) cool and wet Late Holocene (ca. 3 kyr BP). The abundance and diversity of the ostracodes will be used as an additional bioindicator for paleoenvironmental reconstructions of the Siberian Arctic.本次研究对采自拉普捷夫海别科夫斯基半岛的富冰多年冻土沉积物样品开展了介形类（ostracode）分析。研究覆盖了一条厚度达38米的多年冻土序列主体复合剖面，其沉积记录对应晚第四纪过去约6万年的时段。该介形类组合与欧洲第四纪冷期湖相沉积中已知的组合特征相似。介形类的栖息环境为分布于低中心冰楔多边形或小型热喀斯特洼地中的小型浅水环境，其水体寒冷且贫营养。本次研究共计从65个样品中鉴定出7个属、15个分类单元。研究剖面被划分为6个介形类带，这些介形类带与其他古环境代用指标所确立的晚第四纪气候与环境冰阶-间冰阶旋回一一对应：(1) 冷干的兹里扬冰阶（距今58~53千年）；(2) 暖干的卡尔金间冰阶（距今48~34千年）；(3) 从卡尔金间冰阶向冷干的萨尔坦冰阶过渡的阶段（距今34~21千年）；(4) 从萨尔坦冰阶向暖干的晚更新世阿勒罗德期过渡的阶段（距今21~14千年）；(5) 从阿勒罗德期向暖湿的中全新世过渡的阶段（距今14~7千年）；(6) 凉湿的晚全新世（距今约3千年）。介形类的丰度与多样性将作为西伯利亚北极地区古环境重建的附加生物指标。